Simple Visual Studio Unit Testing Examples to Get Your Feet Wet

Howdy readers, Lafe here. About once a month, my partner in crime, Rich Seeley, has been doing technical takeovers of this blog. Here's his latest post, which looks at a few Visual Studio unit testing examples.

Unit tests are not universally popular among developers and not everyone uses them. But those who use the method seem to love the process.

"Unit tests allow you to make big changes to code quickly," writes one fan on a blog refuting unit test skeptics. "You know it works now because you've run the tests, when you make the changes you need to make, you need to get the tests working again. This saves hours."

Assuming you are not a total skeptic and at least want to get your feet wet with Visual Studio unit testing, there are resources to help developers step into the waters.


This Walkthrough’s for You

For users of Visual Studio 2005 through 2017, Microsoft offers a Walkthrough for Creating and Running Unit Tests for Managed Code, which promises to "step you through creating, running, and customizing a series of unit tests using the Microsoft unit test framework for managed code and the Visual Studio Test Explorer." You start with a C# project that is under development, create tests that exercise its code, run the tests, and examine the results. Then you can change your project code and re-run the tests.

The walkthrough is comprehensive and provides the code you need for each of these steps:

  • Create the first test method
  • Build and run the test
  • Fix your code and rerun your tests
  • Use unit tests to improve your code

The goal of unit testing is improving code. Optimistically, the walkthrough concludes: "the work that we did improving our test code led to more robust and informative test methods. But more importantly, the extra analysis also led to better code in our project under test."

If you want to see before you do, there are, of course, YouTube videos that will help you get started with Visual Studio unit testing.


Live Unit Testing (LUT) in Visual Studio 2017

Live Unit Testing in Visual Studio 2017 is a Microsoft video with Joe Morris, Visual Studio program manager introducing you to the latest unit test features. He explains that the real-time feedback helps developers be more productive even if they are thrown into a project that they may not have worked on before.

"Imagine you’re fixing a bug in a code base with which you’re not completely familiar. With Live Unit Testing you can know right away as you’re typing code that you’re not breaking any parts of the system,” Morris explains. “Getting this feedback right in the code editor as you type will give you extra confidence and make you more productive."

Morris goes on to explain that with Visual Studio 2017, LUT is "just a click away." From the top level menu bar, you go to test command and click start. But you have control of when live unit testing runs, so you are not stuck with it finding errors in cases where you are refactoring and know the code is broken. A drop down menu gives you options to pause or stop testing, and, of course, restart when you are ready.

LUT gives you icons in the left column of your screen so you see exactly which lines of code are passing or failing. A green check means the line is passing. A red x tells you a line is failing. If no test applies to a line of code, it gets a blue dash.

When you make a change to a line of code, a little clock icon appears in the left column to tell you LUT is running for that line, so you know it is working. When the test is complete, the familiar green check or red x lets you know the result. The test took seconds in the demo. Of course, your results may vary.


LUT Gives You Options

To find out exactly what test or tests the code is failing, you can hover over the red x and a pop-up will show you the test it has failed. Since multiple tests may apply, those that the code is passing will have the green checkmark. You can dive deeper into the failed test to find out what is going wrong to help you with debugging. This can be done without pausing or stopping LUT, which will run in the background.

When working on code for a number of projects, another option in LUT lets you specify just the project you want to test, which speeds up the testing process.

Boosting developer productivity by reducing manual steps for testing was the key feature Morris touted in his demonstration of Visual Studio LUT.

Unfortunately, this is not yet available for all Visual Studio users.

On the video, Microsoft notes: "Live Unit Testing is present in the Enterprise edition of Visual Studio 2017 and it's available for C# and VB projects that target the .NET Framework."

One viewer of the video complained that it is not available in the Community Edition.

Hopefully, the Visual Studio folks at Microsoft will hear his plea.

Posted by Lafe Low on 05/04/2017


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